Finding the Fourth Proportional to 2,665.81, 3,999.05 and 911.15

Step by Step Solution

1. Step 1: Write the proportion equation
   2,665.81 : 3,999.05 = 911.15 : x
2. Step 2: Convert to fraction form
   2,665.81/3,999.05 = 911.15/x
3. Step 3: Cross multiply
   2,665.81x = 3,999.05 × 911.15
4. Step 4: Simplify right side
   2,665.81x = 3,643,709.86
5. Step 5: Solve for x
   x = 3,643,709.86/2,665.81
6. Step 6: Final answer
   x = 1,366.83